A principal project is directed toward gene therapy of the immune deficiency disease caused by the absence of adenosine deaminase (ADA). We have established T-cell lines from ADA-deficient patients and shown that these cell lines are sensitive to deoxyadenosine and are ADA deficient, just as the cells from these patients are in vivo. A murine retrovirus vector gene transfer system has been modified to contain the gene for human ADA. Our data show that such a gene vector system can successfully transfer a functioning human ADA gene into these defective cells with a high efficiency and that such "gene- treated" cells are reconstituted to normal function. We have continued to study Wiskott-Aldrich syndrome (WAS) patients and have developed a new test to detect carriers of this X-linked disease. The test is based on the observation that, although all female somatic cells contain two X chromosomes, only one X chromosome is active in each cell. Using restriction fragment length polymorphisms to distinguish the two X-chromosomes and methylation-sensitive restriction endonucleases to determine which of the X chromosomes was inactivated, we have shown that carrier females of the WAS gene have a predictable unbalanced pattern of X inactivation involving their T lymphocytes, B lymphocytes, and granulocytes. This unbalanced pattern of X inactivation is not seen in normal females and presumably reflects selection against the expression in the carrier females of the X chromosome bearing the mutant WAS gene. Our studies developing and defining the new immunosuppressive drug succinylacetone (SA) have continued. We have found that this agent is perhaps the most potent T- and B-cell immunosuppressive compound available, totally blocking allograft rejection and graft- versus-host disease (GVHD) in F1 animals and preventing GVHD during total allogeneic bone marrow transplantation while allowing normal engraftment and reconstitution to occur. SA is also a very potent inhibitor of both primary and second antibody responses. Experimental trials of SA use in autoimmune disease have shown that it is remarkably effective in preventing a type of uveitis that usually results in blindness in experimental animals.